Know what pulse rate is doing what?

by Frank Horwill

A heart rate monitor is not essential in the pursuit of maximum fitness. If this were the case, we have to ask how former British world record holders like Roger Bannister achieved their success without ever using the clever device. And, Peter Coe, father and coach to the current Commonwealth 800 and world 1,000 metres record holder, Seb Coe, not only never used the invention but is openly hostile to its use. Peter Coe pointed out in an interview with an athletics magazine that using a heart rate monitor in competition could actually be a hindrance. This is because before a competition there is a thing called "psyched up heart rate". In other words, the pulse at rest is some ten beats faster than normal. If this were the case and an athlete relied on a certain rate, ascertained from using the monitor in training, to run a marathon at a certain pulse level, the athlete would get a shock when the time of the first 10k was announced – it would be much slower than planned. For the simple reason that the planned percentage of the maximal heart rate for the event would be reached much sooner than in training, therefore the pace would be slower. In such cases, the athlete would do better to concentrate on times at various stages of the race.

The correct use of a pulse monitor revolves around an essential factor – the athlete must know what maximum possible pulse rate he or she can achieve. Now, it was once thought that running 400 or 800 metres at full effort would register a maximum. Well, it’s not far off; however, these two distances when run at full effort, produce a lot of lactic acid very quickly which seems to retard the pulse rate reaching maximum. A recent research finding from Sweden suggests that running full out for 3 minutes is more likely to register maximum.

If the athlete declines to do a maximum pulse rate outing, it must be calculated. The old method was to take 220 beats per minute as maximum, and then to subtract from that figure one’s age. So, a female aged twenty five years would have this formula: 220 minus 25 = 195 bpm maximum. This is close but not close enough! Recent research suggests a more accurate estimation – 209 beats per minute maximum minus point seven for every year of age – 209 minus 25 x 0.7 (17.5) = 191.5 bpm: this is less than the old calculation.

The figure for males is 214 bpm minus point eight for every year of age. Given a male aged twenty five, the formula would be: 214 minus 25 x 0.8 (20) = 194 bpm. Note that the old formula is more accurate for men than women.

Pulse rates are intricately linked with work done at a percentage of V0₂ max. They are closely linked with training at what is called the lactate threshold. This is a point in our training when the blood starts to get more and more saturated with lactic acid. The idea of lactate threshold running, sometimes called lactate response running, is to run for about 4 miles (6.5 km) just short of this sudden lactate increase point. By so doing, we eventually "push" or delay the point of lactate increase. In practical terms this means we can run faster (at a slower pulse rate) than before without incurring a lactate penalty. Twelve weeks of once-a-week lactate threshold running will boost fitness levels which may not be detected in a V0₂ max test. It also has the advantage of not being so fast as track repetitions thereby reducing injury risks.

We must now ask how the aforementioned world record breakers achieved their success without the use of a pulse monitor? The answer is that they trained at speeds which were a percentage of their V0₂ max and in doing so, elevated their pulse rates to the required point. For example, if a 3k runner wished to improve his time from 8:30 to 8:15, by running 3 x 1,500m in 4:07.5 with 3 mins rest, it would be 100 per cent of his V0₂ max and would involve the pulse rate achieving maximum.

If we take the example of the 25 year old female above with an estimated maximum of 191bpm, we can plan out what pulse rates should be used to record specific percentages of V0₂ max. In doing this, we must remember one vital criteria – the greatest fitness gains come from work between 90 and 100 per cent of the V0₂ max. Most of the world’s physiologists favour the figure of 95 per cent of the V0₂ max (about 5K speed); however Russian coaches working with female athletes favour 100 per cent of the V0₂ max (about 3K speed). We also come to another important point – the lower the V0₂ max percentage of work – the greater the duration of the repetition. Thus, an athlete training at 90 per cent of his or her V0₂ max (about 10K speed), should do 4 x 10 minutes at 10K speed with very short recovery (about 90 seconds). The minimum duration of any repetitions between 80 – 100 per cent of the V0₂ max is 3 minutes. But work at the lower end of that scale (80%) would be much longer, e.g. 3 x 20 minutes (about half-marathon speed), with extremely short recovery (about 60 seconds).

Here is a table of pulse rates related to percentage of V0₂ max and examples of actual pulse requirements for a female aged twenty-five years with an estimated maximum pulse rate of 191bpm.

A rule-of-thumb rough guide is to remember that whatever the percentage of the V0₂ max is required, the percentage of the pulse rate is that figure plus, so that given a workout at 80 per cent, the required pulse rate starts at 80 per cent maximum plus about 10 beats more.

When we come to calculating what speed and pulse rate our lactate threshold runs should be, there is much to put us off! Ideally, we require a sports physiologist or coach with a portable lactate measuring computer to decide from a sample of an athlete’s blood at what speed of running lactate starts to increase markedly. Failing that, there is a thing called the Conconi Test, where an athlete runs with a heart-rate monitor increasing speed every 200 metres by 2 seconds, and from a slow start involves about 2,400 – 3,200m of running during which time about sixteen pulse measurements are taken. The 200 metre times have to be converted into km/h. The formula being: v=720/t (t=split time). A graph is then drawn of the heart-rate on the left vertical and the km/h values at base. The breakaway point from the linear is known as the "deflection point". The test is subject to human error on many counts. But, analysis is made easier when an interface and an IBM compatible computer are available. There are computer programmes on the market – such as HRCT Leuenberg Medicine Technique AG, that make an automatic analysis of the test possible.

A greatly under-rated method of calculating lactate threshold speed is a table drawn up by the notes physiologist Jack Daniels (USA), who uses the 3K or 2 mile time of an athlete to assess what the lactate response should be. The author has compared the findings of this table with known blood sample readings of some of Britain’s leading athletes and they were identical.

A rule-of-thumb method is to take this 3K time per mile and to add 22 seconds to it, this is about 90 per cent accurate. For example, given a 3K time of 8:30 (68 secs per 400m), this is about 4:34 per mile + 22 seconds = 4:56 per mile (close to the tabulated value of 4:53) for 4 miles on a lactate response run. A person with a time of 11:15 for 3K (90 secs per 400m), about 6 minutes per mile pace, however, needs to add about one minute to that figure i.e. 7 minutes a mile, for 4 miles. Once past 9:15 for 3K the lactate response run per mile rapidly slows. Here is a table of accurate recommendations:

Many heart-rate monitor devotees may have never run in a 3K race and, therefore, Daniels’ table will be of little use. But there is more to this table than at first meets the eye. If we look at the mile differential column of the table, it will be noted that a 7:30 3K runner who will be running at about 4:01 a mile in that event, is only going to be running 15 seconds slower per mile on a lactate response run (4:16 per mile)! That’s 5K pace and 95 per cent of the V0₂ max AND 93 per cent MHR.

If we take one more example, a 11:15 3K performer (6:02 per mile), the lactate response run is 6:54, some 52 seconds per mile slower than 10K speed, about 85 per cent of the V0₂ max, about 90 per cent MHR. This last calculation has led some physiologists to a rule of thumb recommendation for lactate response runs: "Run about 10 seconds per mile slower than per mile for your best 10K time." This may be apt for the 37:30 plus 10K performer, but not for those who are much speedier.

What it boils down to is this: if an athlete can run for more than 30 minutes at 80 per cent of maximal heart rate – that run is not a lactate threshold run: it’s a useful outing, but will do nothing to improve the lactate threshold. Moving the run up to 85 per cent MHR should be tried and if the athlete can just make 4 miles distance at that rate and no further, the target pattern has been set.

One winter, Yvonne Murray, GB International (8:29.02/3K), had her lactate response runs set (by blood analysis) at 5:20 per mile. Six months later it was set at 4:53 per mile. This shows what can be achieved with regular lactate threshold running done correctly.

Where a pulse monitor scores over the stop-watch is when running into a stiff wind. While the timer per mile advocate will struggle to keep to the schedule the pulse monitor athlete will keep to the required pulse-rate even though the speed of running may decline – but the effort remains constant. This is a valuable preventative of over-training.

As a matter of interest, in South Africa (where the author has lectured and coached on numerous occasions) there are heart-rate monitor clubs, i.e. you cannot be a member of the club unless you purchase a monitor from them. All training is done by pulse readings. These clubs are run on a franchise system: a person applies to the heart-rate manufacturers for a franchise using their name to sell the equipment and start a club. A new member, having purchased the monitor receives instructions on its use, which requires an annual club membership fee. A club with a membership of five hundred who have purchased the required monitor and paid the annual fee, nets the club’s founder a handsome livelihood of around £25,000 (R200,000) a year! Enough to boost most pulse rates above resting rate!

Frank Horwill